Orifice plate for an ink-jet pen

Abstract

Selected portions of the orifice plate surfaces are formed to have wetting and non-wetting surface characteristics for minimizing the accumulation of residual ink on the outer surface of the plate and for enhancing the flow of supply ink to the orifices of the plate.

We claim: 
     
       1. An orifice plate for an ink-jet pen, comprising: a plate having an inner surface and an outer surface, the inner surface having an inner surface portion defining an orifice that extends through the plate between the inner surface and outer surface;   the outer surface having a first outer surface portion surrounding the orifice, a second outer surface portion surrounding the first outer surface portion, and a third outer surface portion surrounding the second outer surface portion, the second outer surface portion being less wettable with respect to ink than the first outer surface portion and third outer surface portion; and   the orifice and the outer surface joining to define an edge, said first outer surface portion being adjacent to the edge and separated from the orifice by the edge.   
     
     
       2. The plate of claim 1 wherein the first outer surface portion has a first wetting characteristic is such that ink on a surface having the first wetting characteristic forms a contact angle of less than 70°. 
     
     
       3. The plate of claim 1 wherein the second outer surface portion has a second wetting characteristic is such that ink on a surface having the second wetting characteristic forms a contact angle of greater than 70°. 
     
     
       4. The orifice plate of claim 1 wherein the inner surface portion has a first wetting characteristic with respect to ink. 
     
     
       5. The orifice plate of claim 1 wherein the inner surface portion adjacent to the edge is more wettable with respect to ink than the second outer surface portion. 
     
     
       6. The orifice plate of claim 1 wherein the first outer surface portion adjacent to the edge has a width of between about 30 and 80 microns. 
     
     
       7. An orifice plate for an ink-jet pen, comprising: a plate having an inner surface and an outer surface and defining an orifice that extends through the plate between the inner surface and outer surface;   the outer surface having a first outer surface portion surrounding the orifice and facing generally away from the inner surface, a second outer surface portion surrounding the first outer surface portion, and a third outer surface portion surrounding the second outer surface portion,   the first outer surface portion and second outer surface portion having different wetting characteristics with respect to ink such that the first outer surface portion is more wettable than the second outer surface portion, with the third outer surface portion being more wettable than the second outer surface portion.   
     
     
       8. The orifice plate of claim 7 wherein the first outer surface portion is wetting. 
     
     
       9. The orifice plate of claim 7 wherein the third outer portion portion is wetting. 
     
     
       10. The orifice plate of claim 7 wherein the first outer surface portion has a contact angle of less than 70 degrees. 
     
     
       11. The orifice plate of claim 7 wherein the first outer surface portion has a contact angle between 20 and 50 degrees. 
     
     
       12. The orifice plate of claim 7 wherein a distance between the orifice and the second outer surface portion is between about 30 and 80 microns. 
     
     
       13. The orifice plate of claim 7 wherein the first outer surface portion is an annulus having a width between about 30 and 80 microns. 
     
     
       14. The orifice plate of claim 7 wherein the second outer surface is spaced apart from the orifice by a distance of no greater than about 80 microns. 
     
     
       15. The orifice plate of claim 7 wherein the second portion has a contact angle greater than 70 degrees. 
     
     
       16. An orifice plate for an ink-jet pen, comprising: a plate having an inner surface and an outer surface and defining an orifice that extends through the plate between the inner surface and outer surface, the orifice joining the outer surface at an edge; and   the outer surface having a first outer surface portion adjacent the orifice and separated therefrom by the edge, a second outer surface portion adjacent the first outer surface portion, and a third outer surface portion adjacent the second outer surface portion;   the first outer surface portion and third outer surface portion each having a contact angle with respect to ink which is less than the contact angle of the second outer surface portion, such that the first outer surface portion and third outer surface portion are more wettable with respect to ink than the second outer surface portion.   
     
     
       17. The orifice plate of claim 16 wherein the first outer surface portion has a contact angle of less than 70 degrees. 
     
     
       18. The orifice plate of claim 16 wherein the first outer surface portion has a contact angle between 20 and 50 degrees. 
     
     
       19. The orifice plate of claim 16 wherein the second outer surface portion has a contact angle greater than 70 degrees.